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Cows on a green globe

How spherical-cow philosophy makes hard physics problems easy

There's an old physics joke involving a spherical cow. Though it isn't side-splittingly funny, it does explain why physics works so well, writes Sean Carroll

News

Across the universe. Traveling in space. Time travel. Elements of this image furnished by NASA.; Shutterstock ID 200832383; purchase_order: -; job: -; client: -; other: -

Space

Why general relativity is known as a background independent theory

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This image may not be used in educational posters Double-slit experiment Computer illustration showing a plane wave (bottom right) passing through a gap in a screen, and the resultant circular wave then passing through a screen with two gaps. The gaps act as new wave sources and the wavefronts bend to create two sets of circular waves radiating outwards. These two new waves create an interference pattern as they interact. At the point where a wave peak from one hits a wave peak from another, or a trough hits a trough, they reinforce each other; their magnitudes are summed. This is known as constructive interference. Where a trough hits a peak or vice versa and they cancel each other out. This is known as destructive interference.

Physics

Can particles really be in two places at the same time?

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2F8Y7GF Spacetime Scifi Digital Arts concept, Twist clock time distortion warp on space bended curved as hole represent Space and Times of Einstein Theory

Physics

What does it mean when we say that space-time is expanding?

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Illustration of a clock in a spiral

Physics

Time loops may not be forbidden by physics after all

News

Contemplating the mysteries of the fourth dimension is time well spent

Physics

Contemplating the mysteries of the fourth dimension is time well spent

Leader

How do we make the most of our time? The power of confronting death

Life

How do we make the most of our time? The power of confronting death

Features

Why does time fly or drag? How emotions warp our temporal perceptions

Mind

Why does time fly or drag? How emotions warp our temporal perceptions

Features

5 Evolution - How long does evolution take? 2E8WW3F Time, traveling through space and time, 3d illustration

Earth

How long does evolution take? It happens on two different timescales

Features

8 Can we live without time?

Mind

Can we live without time? Not if we value a solid sense of self

Ditching artificial light and living by the natural cycle of the sun can offer plenty of benefits for your health. But when you lose any sense of time whatsoever, you risk losing yourself too

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Physics

Jun Ye interview: What use is the world's most accurate clock?

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Physics

Will time ever end? The answer lies in the death throes of the cosmos

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Physics

Will we ever unite physics? Clocks in superposition could offer clues

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Physics

Could we ever go back in time? Relativity does not rule it out

Features